Cellular or wireless telecommunication systems have recently introduced a prepayment architecture that allows a subscriber to prepay for services. An advantage services for the wireless operator with prepaid is that the operator obtains payment in advance saving costly collection services or having to obtain security such as credit card information from a subscriber. The subscriber pays as he uses the system avoiding basic monthly service charges when usage is low.
The current prepaid architecture, in use in many cellular wireless telecommunication systems stores a pre-payment made by a subscriber in a prepaid administration server (PPAS) as a time duration value. In other words, the funds are correlated to specific amounts of time that correspond to rates available to the subscriber, i.e., long distance, local, international, etc. When a prepaid subscriber initiates a call, a switching node of the wireless telecommunication system obtains the credit balance of the subscriber from the stored credit balance as a time interval value. The switching node determines the service charging rate for the call depending on the service the subscriber is requesting and applies this charging rate as a timer decrement. That is, the timer is set at the current credit balance and the balance is decreased at a rate corresponding to the service requested each time that the subscriber uses the service. The caller continues to use the prepaid wireless service up to the amount of funds available in the account. When the timer reaches zero time, representing a nil credit balance, then the call is cleared or ended by the switching node. When the account becomes depleted of funds, additional deposits may be made to replenish the account balance.
There are however, several disadvantages associated with traditional prepaid wireless accounts. First, the caller may be required to enter an additional authorization code or personal identification number (PIN) in order to place each call. Another disadvantage to the traditional system is that the subscriber incurs charges when an incoming call is diverted to the subscriber's associated voice mail number. The subscriber is then charged twice for the same call—as the call is received into voice mail and when the subscriber retrieves the message.
It would be desirable therefore to provide an option in a prepaid system that allows a subscriber to receive a voice mail without charge.